Cannot install snap from an unlisted channel but can refresh to unlisted channel

[Callahan Kovacs]

I cannot install LXD from an unlisted channel. I have to install from a listed channel, then refresh to the unlisted channel.

The first error message below may be the same as https://bugs.launchpad.net/snapstore-server/+bug/2001725, but this bug report is about the fact that we can't directly install a snap from an unlisted channel.

```
# remove lxd
> snap remove lxd --purge
lxd removed

# install unlisted channel
> snap install lxd --channel=5.9/stable
error: snap "lxd" is not available on 5.9/stable but is available to install on the following
       channels:

       5.9/candidate snap install --channel=5.9/candidate lxd
       5.9/beta snap install --channel=5.9/beta lxd
       5.9/edge snap install --channel=5.9/edge lxd

       Please be mindful pre-release channels may include features not completely tested or
       implemented. Get more information with 'snap info lxd'.

# install listed channel
> snap install lxd --channel=latest/stable
lxd (stable) 5.10-b392610 from Canonical✓ installed

# now refresh to the unlisted channel
> snap refresh lxd --channel=5.9/stable
lxd (5.9/stable) 5.9-9879096 from Canonical✓ refreshed
```

This bug was uncovered by rockcraft's CI, which installs LXD 5.9 for spread tests and started failing to install last week.

I wasn't sure if this belongs in snapstore-server or snapd, so apologies if it is in the wrong category.

Thanks!

[Daniel Manrique (roadmr)]

Hi,

There is no concept of an "unlisted channel". I checked and the 5.9 track was closed in January; so I think these are meant to be uninstallable by channel. This sounds like a bug in our logic in that it allows refreshing to a closed channel.

No worries, we'll fix it so it can't be installed or refreshed from closed channels.